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AbstractEnergy-efficient desalination technologies are needed to address the growing requirements of potable water owing to population increase, industrial development, and increasing energy cost. Capacitive deionization (CDI) technique is receiving attention because it offers an energy-efficient method of removing dissolved salts by electro-adsorption. The technique has been explored for ground water with total dissolved solids (TDS) of 500–1,500 mg/l, typical of rural areas in India. We have therefore undertaken development of a test cell and report its use for electro-sorption of dissolved ions in groundwater. The active material used is mesoporous carbon aerogel having surface area ~2,000 m2/g, developed in house. The carbon aerogel-based electrodes have shown high salt adsorption capacity of 8.4 mg/g with NaCl electrolyte. CDI cell modules of 500 ml capacity with eight-electrode stack have been used in single and multiple stages, depending on the ground water TDS. Water having salt concentration of 1,500 mg/l was treated to achieve output of ~238 mg/l with power consumption ~0.5 kWh/m3. The low power requirement, chemical free regeneration, and applicability for the ground water make this system of potential interest for addressing the issue of potable water in rural and remote areas.

Energy-efficient desalination technologies are needed to address the growing requirements of potable water owing to population increase, industrial development, and increasing energy cost. Capacitive deionization (CDI) technique is receiving attention because it offers an energy-efficient method of removing dissolved salts by electro-adsorption. The technique has been explored for ground water with total dissolved solids (TDS) of 500–1,500 mg/l, typical of rural areas in India. We have therefore undertaken development of a test cell and report its use for electro-sorption of dissolved ions in groundwater. The active material used is mesoporous carbon aerogel having surface area ~2,000 m2/g, developed in house. The carbon aerogel-based electrodes have shown high salt adsorption capacity of 8.4 mg/g with NaCl electrolyte. CDI cell modules of 500 ml capacity with eight-electrode stack have been used in single and multiple stages, depending on the ground water TDS. Water having salt concentration of 1,500 mg/l was treated to achieve output of ~238 mg/l with power consumption ~0.5 kWh/m3. The low power requirement, chemical free regeneration, and applicability for the ground water make this system of potential interest for addressing the issue of potable water in rural and remote areas.

AbstractElectrodes synthesized using mesoporous carbon aerogel (CA), microporous-activated carbon (AC), and different combinations of the two were evaluated for capacitive deionization application. Composite electrodes with CA and AC in the ratio of 75:25 provided the highest specific capacitance value (90 F/g at scan rate of 2 mV/s). Further, it was observed that on increasing the scan rates to up to 10 mV/s, the reduction in specific capacitance values for the electrodes with 75:25 CA/AC composition was only 5%, whereas the reduction for pure CA and pure AC electrodes were 23 and 52%, respectively. The test cell made using 75:25 CA/AC composite electrodes (size 10 cm × 10 cm with material loading of 15 mg/cm2) showed fast adsorption and desorption cycle of ∼15 min and salt removal efficiency of 51% was obtained.

Electrodes synthesized using mesoporous carbon aerogel (CA), microporous-activated carbon (AC), and different combinations of the two were evaluated for capacitive deionization application. Composite electrodes with CA and AC in the ratio of 75:25 provided the highest specific capacitance value (90 F/g at scan rate of 2 mV/s). Further, it was observed that on increasing the scan rates to up to 10 mV/s, the reduction in specific capacitance values for the electrodes with 75:25 CA/AC composition was only 5%, whereas the reduction for pure CA and pure AC electrodes were 23 and 52%, respectively. The test cell made using 75:25 CA/AC composite electrodes (size 10 cm × 10 cm with material loading of 15 mg/cm2) showed fast adsorption and desorption cycle of ∼15 min and salt removal efficiency of 51% was obtained.